st: Using -exapand

Hi,
I am trying to use -expand to replicate observations:
Focalfirm Technology year n
------------- -------------- --------- -------------
Toyota XYZ 1990 1
Toyota XYZ 1991 4
Toyota ZZZ 1990 --
VW ABC 1999 2
VW CDE 1998 3
The idea is that I want to repeat each observation n times. However,
the new observation must have an updated year number too. That is, the
second observation must be repeated 4 times (including the original
observation, of course), but the year must be updated. So, the next
observations would be identical to the original one, except that their
year will be 1992, 1993 and 1994.
Using -expand,
-expand n, generate(id)
this is what I get
Focalfirm Technology year n id
Toyota XYZ 1990 1 0
Toyota XYZ 1991 4 0
Toyota ZZZ 1990 0
VW ABC 1999 2 0
VW CDE 1998 3 0
Toyota XYZ 1991 4 1
Toyota XYZ 1991 4 1
Toyota XYZ 1991 4 1
VW ABC 1999 2 1
VW CDE 1998 3 1
VW CDE 1998 3 1
This is fine, except that the years are not updated. Any idea how I can do this?
Thanks,
James
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